Re: WAL and commit_delay

On Sun, 18 Feb 2001, Tom Lane wrote:

> I think that there may be a performance advantage to pre-filling the
> logfile even so, assuming that file allocation info is stored in a
> Berkeley/McKusik-like fashion (note: I have no idea what ext2 or
> reiserfs actually do).

ext2 is a lot like [UF]FS.  reiserfs is very different, but does
have similar hole semantics.

BTW, I have attached two patches which streamline log initialisation
a little.  The first (xlog-sendfile.diff) adds support for Linux's
sendfile system call.  FreeBSD and HP/UX have sendfile() too, but the
prototype is different.  If it's interesting, someone will have to
come up with a configure test, as autoconf scares me.

The second removes a further three syscalls from the log init path.
There are a couple of things to note here:* I don't know why link/unlink is currently preferred over  rename.  POSIX
offersstrong guarantees on the semantics  of the latter.* I have assumed that the close/rename/reopen stuff is only
therefor the benefit of Windows users, and ifdeffed it  for everyone else.
 

Matthew.